In a PICOR system for transferring wide-band sound signals, a sound signal is divided into a lower and a higher frequency range and the partial signal of the lower frequency range is transferred directly and instead of the partial signal of the higher frequency range, the amplitude information of partial frequency ranges obtained by splitting up said higher frequency range by means of band-pass filters is transferred by periodic sequential modulation of a single subcarrier with the amplitude information.
At the reproducing end, said subcarrier is demodulated and the amplitude information is separated again by a time selection operating synchronously with the sequential modulation at the pick-up end. The amplitude information of the partial frequency ranges serves as a modulating signal for equivalent signals lying approximately in the center of the individual partial frequency ranges. The modulated equivalent sound signals of the partial frequency ranges of the higher frequency range are added to the directly transferred sound signal of the lower frequency range for reproduction of the total signal.
For such a system using sequential transfer of the amplitude information it has already been proposed to transfer the signal serving for synchronization together with the sound signal. In that case care must be taken that the sync signal is separated from the other signals so as to be capable of being unambiguously evaluated and, on the other hand, remains inaudible although its frequency lies in the audible range.
This manner of transfer is advantageous inasmuch as no special time or frequency channel is needed for the sync signal.